the respiratory system

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Across
  1. 6. an important heat-trapping gas
  2. 8. branching blood vessels that form a network
  3. 10. many tiny air sacs of the lungs
  4. 11. where you breath from.
  5. 12. alows oxygen in the air to be taken into the body
Down
  1. 1. air that flows in your body
  2. 2. the major air passages of the lungs.
  3. 3. a long, U-shaped tube that connects your larynx
  4. 4. branches into which a bronchus divides.
  5. 5. the bony framework of the thoracic cavity
  6. 7. the movement of molecules from a region of higher concentration
  7. 9. a thin sheet of material forming a partition.